content: /*
   * Copyright 2016 David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package hu.akarnokd.agera;
  
  import android.support.annotation.NonNull;
  
  import com.google.android.agera.MutableRepository;
  import com.google.android.agera.Updatable;
  
  import java.util.concurrent.atomic.AtomicLong;
  
  /**
   * Holds onto a value and signals Updatables if the value is updated.
   */
  public final class BehaviorMutableRepository<T> extends AgeraTracking<BehaviorUpdatable> implements MutableRepository<T> {
  
      volatile T value;
  
      @NonNull
      @Override
      protected BehaviorUpdatable createWrapper(@NonNull Updatable updatable) {
          return new BehaviorUpdatable(updatable);
      }
  
      @Override
      protected void onAdd(@NonNull Updatable updatable, @NonNull BehaviorUpdatable wrapper) {
          if (value != null) {
              wrapper.update();
          }
      }
  
      @Override
      protected void onRemove(@NonNull Updatable updatable, @NonNull BehaviorUpdatable wrapper) {
          wrapper.cancelled = true;
      }
  
      @Override
      public void accept(@NonNull T value) {
          this.value = value;
          for (BehaviorUpdatable bu : map.values()) {
              bu.update();
          }
      }
  
      @NonNull
      @Override
      public T get() {
          return value;
      }
  }
  
  final class BehaviorUpdatable
  extends AtomicLong
  implements Updatable {
  
      final Updatable actual;
  
      volatile boolean cancelled;
  
      BehaviorUpdatable(Updatable actual) {
          this.actual = actual;
      }
  
      @Override
      public void update() {
          if (getAndIncrement() == 0) {
              long c = 1;
  
              for (;;) {
                  for (long i = 0; i < c; i++) {
                      if (cancelled) {
                          return;
                      }
                      actual.update();
                  }
  
                  c = addAndGet(-c);
                  if (c == 0L) {
                      break;
                  }
              }
          }
      }
  }
  
  
  